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Each Martian year, approximately 30% of the atmosphere's CO 2 mass is in exchange with the polar surfaces through deposition/sublimation (Leighton & Murray, 1966). The seasonal CO 2 polar caps resulting from repeated depositions of snow/ice can extend down to 50°S/N (Piqueux et al., 2015). Temporal variations of the level and volume of snow/ice associated with the deposition/sublimation process can put crucial constraints on the Mars climate system and volatile circulation models. Additionally, this amount of snow and ice is significant enough to cause seasonal deflection of the lithosphere (Wagner et al., 2022). Constraining the level and mass of the seasonal portion of the polar cap is essential in properly modeling this deflection. Measurements of the level of snow/ice of the seasonal polar caps have been made by the Mars Orbiter Laser Altimeter (MOLA) onboard the Mars Global Surveyor (MGS, Smith et al., 2001;Aharonson et al., 2004;, measuring rock shadow lengths in high-resolution images to deduce the seasonal changes in rock heights on the surface (Mount & Titus, 2015), and precise radiative transfer models using imaging spectroscopy (Andrieu et al., 2018). Compared with the latter two that are spatially and temporally limited due to data availability, MOLA data cover the entire polar regions. Based on profile analysis at different latitudina annuli, Smith et al. ( 2001) measured the maximum seasonal level of snow/ice to be ∼1 m at both poles. In a different approach, Aharonson et al. ( 2004) fitted sinusoidal functions with annual and semi-annual terms to MOLA cross-over height residuals and estimated the maximum level to reach ∼1.5 m at the north pole and ∼2.5 m at the south pole.The "cryptic region" at Martian south pole during the southern spring is roughly located from 50° to 210°E and poleward of 70°S (see also Figure 1 of Hansen et al. (2010)). It is so described as it possesses low temperatures

a b s t r a c tPaphiopedilum spicerianum (Rchb. f) Pfitzer has only one wild population with 38 individuals in Pu'er, southern China, and has been closely monitored under the Plant Species with Extremely Small Population project launched in 2005. Immediate conservation actions, including ex situ conservation, pollination observations, and studies of asymbiotic germination, reintroduction and relocation to new habitats have been conducted because the single existing population is threatened by habitat degradation. In this study, next generation sequencing by Illumina MiSeq with primer pair ITS-3 (F) and ITS-4OF (R) amplified ITS 2 region was conducted to identify and explore the associated uncultivatable fungal community structure and dynamics through seasonal and environmental changes. Assessments of the entire fungal communities from different seasons and habitats indicated that the communities were sensitive to changes in habitat but not to seasonal changes. Between plant roots and soil, two independent fungal communities and compartmentalization of microhabitats were detected. Hydrolysable nitrogen, total phosphorous, and water content were the most significant factors for fungal communities. Fungal community change could be related to nutrient requirements and plant phenology. Paphiopedilum spicerianum can associate with a wide range of orchid mycorrhizal fungal genera and is capable of utilizing different genera simultaneously. The low specificity to mycorrhizal fungi in adult Paphiopedilum spicerianum suggests that the choice of locations for new populations might be broader than initially anticipated.